Major Finding: In menopausal women, night sweats were associated with an increased risk of coronary heart disease in analyses adjusted for age (HR, 1.39), multiple variables (HR, 1.33), and cardiovascular risk factors (HR, 1.25). There was no link with hot flushes.
Data Source: An analysis of 10,787 women in two large cohort studies.
Disclosures: The authors did not disclose any financial conflicts of interest.
Night sweats, but not hot flushes, appear to significantly increase the risk of coronary heart disease, based on the results of an analysis of more than 10,000 women in Sweden and the Netherlands.
“Our data show that women with night sweats have a 33% increased CHD risk as compared with asymptomatic women. [Body mass index], blood pressure, and total cholesterol level could not totally explain this association, because after adjustment for these factors, symptoms of night sweats were still associated with a slightly, borderline significantly increased risk of CHD,” wrote Gerrie-Cor M. Gast, Ph.D., and her coinvestigators (Menopause 2011;18:146-51).
The researchers merged two large cohorts of women of menopausal age – the Eindhoven Perimenopausal Osteoporosis Study (EPOS) and the Women's Health in the Lund Area (WHILA) study – to examine possible associations between menopausal vasomotor symptoms (VMS) and risk of CHD. EPOS is a prospective cohort study among 6,700 Dutch women aged 46-57 years, who participated in a screening program established to assess determinants of low bone mineral density during 1994-1995. The WHILA Study comprises 6,917 Swedish women aged 50-64 years who participated in a health screening procedure that took place between 1996 and 2000.
Women with prevalent cases of CHD were excluded, leaving in 10,787 women for the analysis (4,790 from EPOS and 5,997 from WHILA). Both studies were linked to databases that allowed the researchers to gather information about causes of death.
The association between VMS and incident CHD was investigated using Cox regression models; women who reported that they had no VMS were used as the reference category. The analyses were based on a mean follow-up of 10.3 years. In total, 48% of all women reported symptoms of flushing and 35% reported symptoms of night sweats. The overall mean age at baseline was 53 years but the mean baseline age was greater in the WHILA cohort than in the EPOS cohort. Women in the EPOS cohort were more likely to have a medium level of completed education and to be current smokers. All other variables were similar for both cohorts. During follow-up, 303 women experienced an incident CHD event, of which 14 were fatal, noted Dr. Gast, a researcher at the University Medical Center Utrecht in the Netherlands, and her coinvestigators.
The presence of flushing was not associated with risk of CHD (hazard ratio, 1.11). This did not change after multivariable adjustment. However, in the age-adjusted and multivariable-adjusted analyses, the occurrence of night sweats was associated with a significantly increased risk of CHD, with hazard ratios of 1.39 and 1.33, respectively.
Importantly, adjustment for BMI, blood pressure, and total cholesterol level attenuated the association, but symptoms of night sweats were still associated with a slightly, borderline significantly, increased risk of CHD (HR, 1.25).
To minimize the possibility that the use of exogenous hormones modified the risk of CHD, the researchers conducted a separate analysis for the subgroup of 7,100 women who had never used oral contraceptives or hormone therapy. Symptoms of flushing were not associated with risk of CHD in this group.
However, night sweats were still positively and even more strongly associated with a significantly increased CHD risk in the age-adjusted model (HR, 1.46) and multivariable-adjusted model (HR, 1.44) – as well as in the analyses, in which the researchers adjusted for BMI, blood pressure, and total cholesterol (HR, 1.35).
“We do not have a clear pathophysiological explanation for our finding,” the researchers wrote.
They speculated that “a possible mechanism linking night sweats to CHD is the sympathetic nervous system activity, which is thought to be higher in the symptomatic women. An increase in sympathetic nervous system activity is also involved in various vascular abnormalities. Conceivably, this may explain the higher CHD risk in women with night sweats.”
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